//
//  性能检测.h
//  面试题
//
//  Created by Toj on 8/19/21.
//

https://www.jianshu.com/p/af7bb933f1ff
https://blog.ibireme.com/2015/11/12/smooth_user_interfaces_for_ios/

#pragma mark - 目录
1. 性能检测
2. 性能优化


#pragma mark - 1. 性能优化


#pragma mark - 2. 性能检测
2.1 启动时间
2.1.1 在Xcode的Edit scheme中增加DYLD_PRINT_STATISTICS这个环境变量为1
2.1.2 Instrument 里面有个time profiler 也能看到启动时间

2.2 内存占用量，内存告警次数
xcode自带工具就能看到内存的增长
#import <mach/mach.h>
#import <mach/task_info.h>

- (unsigned long)memoryUsage
{
    struct task_basic_info info;
    mach_msg_type_number_t size = sizeof(info);
    kern_return_t kr = task_info(mach_task_self(), TASK_BASIC_INFO, (task_info_t)&info, &size);
    if (kr != KERN_SUCCESS) {
        return -1;
    }
    unsigned long memorySize = info.resident_size >> 10;//10-KB   20-MB

    return memorySize;
}
返回内存 的数值

2.3 CPU使用率
- (float)cpu_usage
{
    kern_return_t           kr = { 0 };
    task_info_data_t        tinfo = { 0 };
    mach_msg_type_number_t  task_info_count = TASK_INFO_MAX;

    kr = task_info( mach_task_self(), TASK_BASIC_INFO, (task_info_t)tinfo, &task_info_count );
    if ( KERN_SUCCESS != kr )
        return 0.0f;

    task_basic_info_t       basic_info = { 0 };
    thread_array_t          thread_list = { 0 };
    mach_msg_type_number_t  thread_count = { 0 };

    thread_info_data_t      thinfo = { 0 };
    thread_basic_info_t     basic_info_th = { 0 };

    basic_info = (task_basic_info_t)tinfo;

    // get threads in the task
    kr = task_threads( mach_task_self(), &thread_list, &thread_count );
    if ( KERN_SUCCESS != kr )
        return 0.0f;

    long    tot_sec = 0;
    long    tot_usec = 0;
    float   tot_cpu = 0;

    for ( int i = 0; i < thread_count; i++ )
    {
        mach_msg_type_number_t thread_info_count = THREAD_INFO_MAX;

        kr = thread_info( thread_list[i], THREAD_BASIC_INFO, (thread_info_t)thinfo, &thread_info_count );
        if ( KERN_SUCCESS != kr )
            return 0.0f;

        basic_info_th = (thread_basic_info_t)thinfo;
        if ( 0 == (basic_info_th->flags & TH_FLAGS_IDLE) )
        {
            tot_sec = tot_sec + basic_info_th->user_time.seconds + basic_info_th->system_time.seconds;
            tot_usec = tot_usec + basic_info_th->system_time.microseconds + basic_info_th->system_time.microseconds;
            tot_cpu = tot_cpu + basic_info_th->cpu_usage / (float)TH_USAGE_SCALE;
        }
    }

    kr = vm_deallocate( mach_task_self(), (vm_offset_t)thread_list, thread_count * sizeof(thread_t) );
    if ( KERN_SUCCESS != kr )
        return 0.0f;

    return tot_cpu * 100.; // CPU 占用百分比
}
2.4 页面渲染时间，刷新帧率
Instrument里的Core Animation查看
2.5 网络请求时间，流量消耗
用链接工具分析你的程序如何使用TCP/IP和UDP/IP链接

2.6 UI阻塞次数，不可操作时长，主线程阻塞超过400毫秒次数


2.7 耗电功率
UIDevice.currentDevice.batteryMonitoringEnabled = true;
NSLog(@"电量：%f%%",[UIDevice currentDevice].batteryLevel * 100);
